The parents of Madeleine McCann are urging supporters to help stop trolls who continue to plague them with vile web abuse which they say is 'so awful and upsetting.'

Kate and Gerry, who face fresh agony as the police hunt into their daughter's disappearance is set to be shelved next month, have approved a set of rules to help curb the online haters.

The couple told recently how they still try to shield their 12-year-old old twins from cruel, false and libellous taunts being made against the family, which Kate describes as 'shocking, striking and quite hard to get your head round.'

Now the McCanns, whose daughter was snatched from a Portuguese holiday resort 10 and a quarter years ago, are pleading with well wishers not to post anything to encourage tormentors.

It comes as a Government launches a crackdown on online abusers. The Crown Prosecution Service has revised its guidelines and is now pressing for the growing trend in cyberspace hate to be treated as seriously as face to face abuse.Kate and Gerry are backing a new 'Rules of the Road' on the official Find Madeleine Campaign website which promotes positive, helpful comments and is now trying to ban trolling.

The digital co-ordinator, a friend of the couple who runs the Facebook page on their behalf, states: 'Please do not feed trolls. Trolls feed on havoc and causing chaos. If we do not feed them they will starve for attention and hopefully spread their hate someplace else.'

Madeleine McCann's parents are targeted by 150 vile tweets every day, according to research into online abuse.

The cruel remarks, directed at Kate and Gerry, were found to be made mostly by women.

Psychologist Dr John Synott, who carried out the first study of its kind and revealed his finding in March, said: 'Most trolling behaviour has a lifespan of a couple of days.'This has gone on for ten years, and you cannot see it ever ending. That is the legacy of the McCann case.

'In the physical world there are repercussions. You couldn't get away with saying these things in the street. But in the virtual world there are no consequences.'

He estimated there were between 100 and 150 abusive comments directed on Twitter, Facebook and online McCann message boards daily.. Much of the abuse blames the couple for being responsible for her their daughter's disappearance.

Dr Synott called for action to be taken against the trolls, including taking away pseudonyms that allowed people to make abusive comments anonymously.